Prosthetic liner and prosthetic shaft system comprising prosthetic liner and prosthetic shaft

ABSTRACT

A prosthetic liner for application on a stump, comprising an elastic base, which has a proximal opening for insertion of the stump in a receiving space, and a distal end. At least one pneumatic piston is arranged on the outer face of the prosthetic liner.

The invention relates to a prosthetic liner for application on a stump,comprising an elastic base body which has a proximal opening, forinsertion of the stump into a receiving space, and a distal end, andalso a prosthetic socket system comprising such a prosthetic liner andprosthetic socket.

Prostheses are used to replace the function and optionally the visualappearance of a missing limb and are attached to the body of thepatient. A variety of possibilities for attaching the prosthesis areknown. A common possibility for attaching prostheses to extremities isthe arrangement on a remaining part of the limb, the so-called stump.The stump is encompassed by a prosthetic socket, which in general isdimensionally stable. An insertion opening is formed on the proximal endof the stump, at least one fixing mechanism is provided on the distalend of the socket, on which further prosthetic components may bearranged, for example joints or other functional units such asprosthetic feet or prosthetic hands. In order to achieve a good fit, amodel of the stump is prepared and the socket is adapted to the contourof the stump model. To compensate for variations in volume, it may beprovided that the socket is made narrower than the molded stump model.

To increase comfort, it may be provided that a so-called prostheticliner is arranged between the prosthetic socket and the stump. Ingeneral, the prosthetic liner comprises a closed base body with aproximal opening and is pulled over the stump in the manner of a sock.The elastic material adheres to the stump surface and generates theconnection between the stump and the prosthetic socket. For attachingthe prosthetic liner to the prosthetic socket, mechanical lockingelements may be provided at the distal end of the prosthetic liner andcorresponding locking mechanisms may be provided at the distal end ofthe prosthetic socket, which positively lock the prosthetic liner to theprosthetic socket after insertion into the prosthetic socket. Theattachment of the prosthetic liner to the prosthetic socket can bereleased via an unlocking mechanism.

A further possibility for attaching a prosthetic socket to a stumpresides in so-called suction socket liner technology, in which theprosthetic socket seals airtight against the prosthetic liner and theair present in the space between the prosthetic liner and the prostheticsocket is sucked or pressed out. Reverse flow is prevented by anon-return valve. It is necessary here to design the prosthetic socketin an airtight manner and to ensure a large sealing area against theprosthetic liner.

US 2011/0035027 A1 relates to a vacuum-assisted liner system with aflexible liner, which is pulled over a stump and which has at least oneperipheral edge. The liner is made of an airtight material and has atleast one porous region which is spaced apart from the peripheral edge,in order to enable the transport of air and moisture between an outersurface and an inner surface of the liner.

US 2012/0191217 A1 relates to a socket system with a vacuum liner forprosthetic or orthotic devices. A region of elastic material is arrangedon the distal end of the closed liner, which material is harder than thematerial of the rest of the liner. The region has a concave sectionwhich extends inward from an outer end surface of the region. The distalregion and the concave section form at least a part of a vacuum pump, inorder to pump air out of the space between the liner and the prostheticsocket.

U.S. Pat. No. 8,197,555 B1 relates to a vacuum pump which is integratedinto a prosthetic socket on the distal end thereof. The vacuum pumpcomprises an elastomer housing with two non-return valves and a springelement made from an elastomeric material. If the spring element isloaded, air is forced through a first non-return valve into anintermediary space and out of an outlet valve from the intermediaryspace into the environment. If the elastomeric spring element isunloaded, the outlet valve is closed and the first non-return valve isopened, and further air is sucked out of the prosthetic socket into theintermediary space. The air in the intermediary space between theprosthetic socket and the prosthetic liner is thereby pumped out.

U.S. Pat. No. 6,979,355 B1 relates to a valve arrangement for aprosthetic mechanism with a prosthetic socket, on the distal end ofwhich is formed a channel which is closed with a valve.

U.S. Pat. No. 6,063,125 relates to an attachment mechanism forprosthetic limbs with a socket and a distal adapter, in which athrough-bore is arranged. A non-return valve is formed within the bore.

DE 10 2006 054 981 A1 relates to a prosthetic socket with active airdischarge, in which a pump chamber is arranged in a side wall of aprosthetic socket and is coupled via a valve to the externalenvironment.

US 2008/0004716 A1 relates to a socket and a liner for attachment to astump. A non-return valve is formed in the socket to transport air outof the socket.

DE 10 2004 056 775 A1 relates to a device for releasably connecting aprosthetic socket to a prosthetic lower part. A spring-loaded piston isguided in a piston chamber at the distal end of the prosthetic socket. Aseal may be arranged on the piston to create a negative pressure inconjunction with a valve in the piston chamber. Elastically pretensionedlatching means are assigned to the piston in order to limit the movementthereof, said latching means latching into latching recesses formed inthe piston.

The object of the present invention is to provide a prosthetic liner anda prosthetic socket system, with which a secure attachment of theprosthesis to the liner can be achieved for passive vacuum sockets, andwhich can provide an improved feeling of retention and also an improvedwearing comfort for the user.

According to the invention, this object is achieved by a prostheticliner with the features of the main claim and a prosthetic socket systemwith the features of the additional independent claim. Advantageousrefinements and developments of the invention are disclosed in thedependent claims, the figures and the description.

In the prosthetic liner for application on a stump, comprising anelastic base body which has a proximal opening, for insertion of thestump into a receiving space, and a distal end, provision is made that apneumatic piston is arranged on the outside of the prosthetic liner.

In a passive vacuum system, i.e. a system in which a vacuum between aprosthetic liner and a prosthetic socket is created by the wearer of theprosthetic himself and the relative movement of the prosthetic linerrelative to the prosthetic socket, a negative pressure is created in theinterior of the socket in the swing phase, in which the prostheticmechanism is moved away from the stump due to centrifugal forces. Aretaining force is generated by means of the negative pressure in theinterior of the socket during the swing phase, which retaining force isresponsible for the attaching effect of the prosthetic liner in theprosthetic socket. This movement can be perceived by users asuncomfortable, because the lifting of the prosthetic socket and theliner leads to a feeling of instability and loose fit. The air from thespace between the prosthetic liner and prosthetic socket is evacuated bythe pneumatic piston, which leads to an improved retaining force. Theresult is a self-regulating system, which is designed to ensure optimumretention between the prosthetic socket and the prosthetic liner. Thepneumatic piston enables a precise guiding of the distal end of theliner with effective pumping action due to the simplified sealability ofthe volume closed off by the pneumatic piston.

A development of the invention provides that the pneumatic piston has ablocking element which prevents a reverse flow of air in the directionof the prosthetic liner. By the arrangement of a blocking element, forexample a valve or circumferential blocking lip, in or on a pneumaticpiston arranged at the distal end of the prosthetic liner, it ispossible to use the relative movement between the prosthetic liner andthe prosthetic socket to increase the negative pressure within theprosthetic socket and thereby to reduce the lifting of the prostheticliner from the inner wall of the prosthetic socket. The air from thespace between the prosthetic liner and prosthetic socket is evacuated bymeans of the piston, which leads to a compact structure in whichessential components for the evacuation are integrated into thepneumatic piston.

The pneumatic piston may be configured as a separate component andattached to the prosthetic liner; in particular the respective pneumaticpiston may be reversibly attached to the distal end or in the distal endregion of the prosthetic liner. Through a reversible attachment orattachment possibility to the prosthetic liner, it is possible to attachdifferent sized pneumatic pistons to the liner in order to enable anadaptation to the respectively necessary retaining force or thenecessary pump volume. At least one attachment mechanism is formed onthe prosthetic liner and correspondingly on the pneumatic piston for thereversible attachment of the pneumatic piston to the prosthetic liner.The attachment mechanism may be formed, for example, as a screw system,a click system with a ball head bearing, a positive locking via velcroclosures or a hook system with corresponding receptacle and positivelocking.

In addition to the reversible attachment of the pneumatic piston to theliner, it is possible to form this in one piece with the liner or tofirmly bond it thereon. For this purpose, the pneumatic piston may beattached to the prosthetic liner via an elastic shaft, so that smallmisalignments between the pneumatic piston and the prostheticsocket-side receptacle can be compensated. By means of a one-piececonfiguration, it is possible to dispense with a separate mounting and aseparate coupling element. In an elastic binding of the pneumatic pistonto the prosthetic liner, a bringing together of the prosthetic linerwith the prosthetic socket is facilitated, as slight misalignments ofthe pneumatic piston can be compensated by the material elasticity.

The blocking element assigned to the pneumatic piston is formed as avalve in or on the pneumatic piston or as a blocking lip functionssimilarly to an air pump and allows air to flow into the closed volumeduring a suction movement and comes into contact with the cylinderregion during a discharge movement and thereby effects a seal.

In order to ensure a secure attachment of the pneumatic piston to theprosthetic liner and moreover to enable a sufficient stability and forcedistribution from the distal end of the prosthetic liner to the stump, adimensionally stable end cap is provided on the distal end in adevelopment of the invention, onto which the pneumatic piston isattached. The attachment may be carried out via the above-describedattachment mechanisms. In principle, it is also possible that thepneumatic piston is formed on the distal end of the prosthetic liner orthe end cap, so that a very compact construction results.

The pneumatic piston may have at least one circumferential sealingelement, in particular an O-ring, by means of which the volume betweenthe pneumatic piston and the cylinder region of the prosthetic socketcan be sealed. In principle, it is also possible and provided that thepiston may also function without a sealing element in the cylinderregion, if the accuracy of fit is sufficiently high.

A development of the invention provides that the pneumatic piston ismovably attached to the prosthetic liner, for example via a ball jointor an elastomeric element. The movable attachment may here occurdirectly on the prosthetic liner or on an end cap arranged thereon. Bymeans of a ball joint, it is possible that the pneumatic piston mayalways be moved perpendicularly within a corresponding cylinder regionin the prosthetic socket, without a tilting of the pneumatic pistonwithin the cylinder region. At the same time, a reversible connectionbetween the pneumatic piston and the prosthetic liner may occur via theball joint, since the prosthetic liner-side attachment element is formedas a ball head, onto which a pneumatic piston, which has been providedwith a corresponding receptacle, is clipped. In addition to a mountingvia a ball joint, which in general enables a rotation about a pivotwithout resetting forces, an elastic connection of the pneumatic pistonto the prosthetic liner is possible, for example via an elastic web,pins, bolts or the like. In addition to a relative displaceability ofthe pneumatic piston to the prosthetic liner, a guiding and centeringwithin the prosthetic socket is also provided by the elastic connection.

A development of the invention provides that the pneumatic piston isattached to the prosthetic liner via at least one magnet. Via themagnetic, i.e. force-locking, attachment of the pneumatic piston to theprosthetic liner, for example to a pin of an end cap, it is possible toeasily connect different prosthetic liners to the pneumatic piston, sothat a standardized pneumatic unit can be coupled to differentprosthetic liners, or vice versa. By means of the magnetic coupling, itis also possible to perform a relatively easy replacement of individualcomponents.

In one embodiment of the invention, the pneumatic piston is or can beconnectably integrated via at least one magnet into a prosthetic socketsystem composed of the prosthetic liner, in particular as it isdescribed above, and a prosthetic socket.

In order to allow a displaceability similar to that of a ball joint in amagnetic connection of the pneumatic piston to the prosthetic liner,such that the pneumatic piston itself can always be guided straight intothe receiving part, in particular in the cylindrical region of thereceiving part, a spherical surface is provided at least in parts on thepneumatic piston, which surface may either be convex or concave. Amovability and a certain displaceability is possible by means of thespherical surface due to the magnetic connection, so that rotationalforces are not directly transferred to the pneumatic piston, so that acanting cannot take place, or only takes place in extreme situations.

An attachment element may be arranged on the prosthetic liner, via whichelement the pneumatic piston is attached to the prosthetic liner andwhich has a contact surface formed to correspond to an at leastpartially spherical surface of the pneumatic piston. Through the convexcontact surface in a concavely-formed spherical surface of the pneumaticpiston or vice versa, it is possible to perform a ball joint-likemovement of the pneumatic piston about the attachment element, so that arelative displacement of the prosthetic liner to the pneumatic pistonwith respect to the possible axes of rotation is always provided.

The connection between the prosthetic liner and the pneumatic piston mayoccur as the user gets into the prosthetic socket, so that as soon asthe user of the prosthesis gets into the prosthetic socket, theprosthetic liner or the attachment element brings the contact surfaceinto contact with the magnets on or in the pneumatic piston. Even whenthe piston is at rest in the lower position, the magnetic forces aregenerally sufficient to move the piston back to the upper position. Ingeneral, however, the pneumatic piston is in the upper position, becausethe piston is located there when the prosthetic socket is exited. Whenthe prosthesis user exits the prosthetic socket, a separation of theprosthetic liner from the pneumatic piston may easily occur through apulling-out movement, which merely has to apply a force which is greaterthan that exerted by the retaining magnets in the pneumatic piston or inthe attachment element.

In the prosthetic socket system having a prosthetic liner forapplication on a stump, comprising an elastic base body which has aproximal opening, for insertion of the stump into a receiving space, anda distal end, and a prosthetic socket which forms an intermediary spacewith the prosthetic liner, provision is made that at least one pneumaticpiston is arranged on the outside of the prosthetic liner and that theprosthetic socket has a cylinder region corresponding to the pneumaticpiston, which cylinder region is formed to receive the pneumatic pistonand in which a closed volume is formed in the coupled state of theprosthetic liner with the prosthetic socket, which closed volume iscoupled to at least one blocking element which prevents a reverse flowof air into the intermediary space. The prosthetic liner may be designedas described above or may also function without an integrated valve orintegrated blocking lip in a corresponding design of the cylinderregion. The corresponding cylinder region is formed such that thepneumatic piston may glide on the inside of the prosthetic liner along asealing element, in order to push air out of the closed volume.

According to the invention, it is provided that the pneumatic pistonforms a closed volume together with the corresponding cylinder region onthe prosthetic socket, which closed volume, by means of a blockingelement, in particular a non-return valve, draws air in from the regionbetween the prosthetic socket and the prosthetic liner during a volumeexpansion, for example during the swing phase, and expels it again bymeans of an equally oriented non-return valve, for example on the end ofthe cylinder region opposite the pneumatic piston, during the stancephase, when an axial loading in the direction of the distal end of theprosthetic socket occurs. The closed volume, which is variable due tothe relative displacement between the cylinder region and the pneumaticpiston, represents the pumping volume which corresponds to the maximumexpulsion volume of a full stroke. The larger the diameter of thepneumatic piston and the greater the possible stroke, the greater thepumping volume and thereby the negative pressure between the prostheticsocket and the prosthesis liner achievable per stroke.

Within the volume, at least one blocking mechanism or at least onefluidic connection to a blocking mechanism may be present, which enablesan outflow of air and prevents a reverse flow. This is possible, forexample, by means of a non-return valve, which can optionally also beopened in order to reduce the negative pressure and the retaining force.By means of the arrangement of a blocking mechanism, an almost silentevacuation is possible, in addition to which it is possible to definethe location at which the air is pressed out of the volume. The blockingmechanism or blocking mechanisms enable a suction of the air out of theintermediary space between the prosthetic liner and the prostheticsocket, and they prevent a reverse flow of air from the environmentthrough the closed volume into the intermediary space.

The closed volume and/or the intermediary space may be fluidicallyconnected to a ventilation mechanism for the introduction of air, inorder to cancel the negative pressure in the closed volume orintermediary space and to introduce ambient air into the closed volumeand/or intermediary space between the prosthetic socket and theprosthetic liner, so that the prosthetic liner can be removed from theprosthetic socket. The ventilation mechanism has an access to the closedvolume and/or directly to the intermediary space of prosthetic liner andprosthetic socket, in order to enable a release of the connection.Alternatively to the use of a ventilation mechanism, the intermediaryspace may be ventilated by removal of a sealing collar, which is used asa proximal seal. If a seal is arranged in the socket or arranged on theliner, a separate ventilation mechanism is necessary.

An insertion bevel may be provided on the proximal end of the cylinderregion to facilitate insertion of the pneumatic piston into the cylinderregion, so that the correct relationship between the stump withprosthetic liner and the prosthetic socket can be easily created. Thepneumatic piston is automatically guided to the cylinder region via theinsertion bevel, and the latter ensures a centering and orienting of theprosthetic liner within the prosthetic socket.

A pull-out safety for the pneumatic piston may be arranged on theproximal end of the cylinder region, preventing the pneumatic pistonfrom being pulled out of the cylinder region during a withdrawal fromthe prosthetic socket. The pull-out safety may be arranged mechanically,in particularly form-lockingly, on the receiving part, for examplescrewed, clamped or clipped in. Advantageously, a circumferentialconfiguration of the pull-out safety is provided by means of ascrewed-on or otherwise fixed ring.

Exemplary embodiments of the invention are explained hereinafter indetail with reference to the accompanying figures. Like reference signsrefer to like components.

FIG. 1 shows a schematic representation of a prosthetic liner and apneumatic piston in a side view;

FIG. 2 shows a sectional view of a pneumatic piston;

FIG. 3 shows a perspective view of a pneumatic piston;

FIG. 4 shows a sectional view through a prosthetic liner during joining;

FIG. 5 shows a perspective view of a receiving part;

FIG. 6 shows a sectional view in the assembled state;

FIG. 7 shows a schematic view of one variant;

FIG. 8 shows a detail view of FIG. 7;

FIG. 9 shows an individual view of the receiving part with pneumaticpiston and end cap;

FIG. 10 shows a schematic sectional view in a first variant;

FIG. 11 shows a schematic sectional view of the prosthetic liner in theassembled state;

FIG. 12 shows a representation of a tilted position with pull-outsafety;

FIG. 13 shows a representation of FIG. 12 in a lowered position;

FIG. 14 shows a representation of FIG. 13 in the lowest end position;

FIG. 15 shows a perspective representation of the position according toFIG. 12;

FIG. 16 shows an oblique bottom view of the position according to FIG.10;

FIG. 17 shows an oblique view of the position according to FIG. 16;

FIG. 18 shows a side view of the position according to FIG. 17;

FIG. 19 shows an oblique top view of a receiving part with insertedpneumatic piston and pull-out safety;

FIG. 20 shows an individual representation of a pneumatic piston;

FIG. 21 shows an oblique bottom view of the pneumatic piston accordingto FIG. 20;

FIG. 22 shows an oblique bottom view of an end cap and a pneumaticpiston; and

FIG. 23 shows a side view of the position according to FIG. 22.

FIG. 1 shows a prosthetic liner 10 with an elastic base body 11, whichmay be made for example of silicone or another elastomer. An opening ispresent at the proximal end 12 of the prosthetic liner, through whichopening a prosthesis user may place a stump in a receiving space withinthe prosthetic liner 10. The receiving space is not shown in thisfigure. In general, the application of the prosthetic liner 10 takesplace by means of a rolling down of the proximal end 12 or by eversionof the proximal end 12, application of a distal end 14 of the prostheticliner to the distal end of the stump and then rolling onto the stump. Inthe example shown, a dimensionally stable end cap 16 is arranged on thedistal end 14 of the prosthetic liner 10, which end cap 16 is used tostabilize and soften the bedding of the stump with respect to theconnection of a pneumatic piston 30 on the outside 15, i.e. the side ofthe prosthetic liner 10 opposite the receiving space. Attachmentmechanisms arranged on the end cap 16 make it possible to arrange thepneumatic piston 30 on the end cap 16. The pneumatic piston 30 likewisehas an attachment mechanism 37, via which the pneumatic piston 30 can beattached to the prosthetic liner 10, in particular to the distal end cap16.

The underside of the pneumatic piston 30 can be seen in FIG. 2; thesealing element 31 at the outer periphery of the pneumatic piston 30 canlikewise be seen. Through the arrangement of the sealing element 31 onthe outer periphery of the pneumatic piston 30, a sealing fitting on acylinder region is possible, so that a pumping effect is brought aboutduring a relative movement between the pneumatic piston 30 and thecylinder region. The pneumatic piston 30 can be reversibly connected viathe attachment elements 17, 37 to the prosthetic liner 10. It is therebypossible to attach different types of pneumatic pistons to the liner.The pneumatic pistons 30 may vary in diameter, shape or choice ofmaterial. In place of a pin, the pneumatic piston 30 may also be screwedin, as a result of which it is possible to use a standard liner aftercorresponding conversion.

The coupling of the pneumatic piston 30 to the prosthetic liner 10 ispreferably formed as a mechanical coupling, for example as a ball headjoint 35; it is also possible that an adhesive connection is formedbetween the components. Alternatively to a separate embodiment of thepneumatic piston 30, it is possible to integrate this directly into thedistal end cap 16, for example through integral forming or moldingwithin the context of a two-component injection molding process. The endcap 16, which is also deformable to a certain extent, may be made fromthe material of the prosthetic liner 10 and may form a continuous systembetween the prosthetic liner 10 and the pneumatic piston 30 in amaterial connection to the pneumatic piston 30. It is also possible andprovided that the attachment element 17 assigned to the prosthetic liner10 is integrally formed with the prosthetic liner 10 or materiallyconnected therewith, for example attached or formed onto the end cap 16.

It can further be seen in FIG. 2 that a fluidic connection 32 in theform of a transverse bore within the pneumatic piston 30 is formed on aprojection or protrusion oriented toward the prosthetic liner 10. Thetransverse bore 32 opens into a bore which is oriented perpendicular tothe main surface of the pneumatic piston 30, so that a fluidicconnection 32 from the ambient atmosphere around the prosthetic liner 10to the distal end face of the pneumatic piston 30 is present. A valve 33in the form of a non-return valve is arranged within this fluidicconnection 32 and permits a flow in the direction toward the distal endface of the pneumatic piston 30 but blocks a reverse flow through thefluidic connection 32. It is thereby possible that air from theenvironment around the prosthetic liner 10, for example from the space60 between the prosthetic liner 10 and a prosthetic socket 20, can besuctioned out and transported into the environment, whereas penetrationof air into this space 60 through the fluidic connection 32 is notpossible. A plurality of transverse bores may be present, so that thefastening elements 37 may be formed as finger-like spring elements, inorder to form the ball joint bearing 35.

In addition to only one sealing element 31 at the outer periphery, aplurality of sealing elements 31 which are spaced axially apart from oneanother may also be arranged at the outer periphery of the pneumaticpiston 30, in order to permit improved guiding in a correspondingcylinder region 21 of a prosthetic socket 20.

FIG. 3 shows a perspective view of FIG. 2, which shows the separateembodiment of the pneumatic piston 30 on the attachment element 17. Theattachment element 17 may be reversibly attached to the prosthetic liner10, in particular the end cap 16.

A sectional view of a detail representation is shown in FIG. 4, in whichthe pneumatic piston 30 according to FIG. 2 is inserted in a cylinderregion 21 of a receiving part 25. The receiving part 25 and the cylinderregion 21, which is formed therein, form the corresponding counterpartto the pneumatic piston 30, which sealingly bears with the sealingelement 31 on the wall of the cylinder region 21. The pneumatic piston30 closes the cylinder region 21 in the proximal direction and forms aclosed volume 50 therewith, which has an outlet valve 51 in the form ofa non-return valve, so that, during a relative movement between thereceiving element 25 and the pneumatic piston 30 in the direction of theoutlet valve 51, the air compressed in the closed volume 50 can bepressed out. If, in the case of an unloading, a relative movement of thepneumatic piston away from the outlet valve 51 takes place, air from thesurrounding area of the prosthetic liner 10, not shown, is transportedthrough the valve 33 into the closed volume 50 by means of the fluidicconnection 32, since a positive pressure has formed relative to theclosed volume 50. Via a reverse movement, the air which is located andcompressed in the closed volume 50 is again discharged via the dischargevalve 51.

An insertion bevel 26 is incorporated into the receiving part 25 on theproximal edge of the cylinder region 21, which insertion bevel 26 formsa radius in the embodiment shown, so that, even with a positioning ofthe prosthetic liner 10 in a prosthetic socket that is initiallyinaccurate, for example during insertion, a suitable and desiredassociation between the pneumatic piston 30 and the cylinder region 21can be realized.

Through the combination shown in FIG. 4 of a sealed pneumatic piston 30and cylinder region 21, a piston pump is formed via which the air can besuctioned out of the surrounding area of the prosthetic liner 10, inparticular out of the space between a prosthetic socket 20 formed as asuction socket and the prosthetic liner 10. If the suction and pumpingprocess is repeated several times, the negative pressure within theprosthetic socket 20 changes with each piston stroke. Due to thereduction of play between the prosthetic liner 10 and the prostheticsocket 20, the piston stroke is gradually reduced, as a return movementof the pneumatic piston 30, i.e. an increase of the volume 50, isgradually reduced. Due to the direct mechanical coupling of thepneumatic piston 30 and the prosthetic liner 10, a stroke movement takesplace until the prosthetic liner 10 no longer moves in the prostheticsocket 20. If this state is reached, it can be assumed that an optimumretaining force between the prosthetic liner 10 and the prostheticsocket 20 has been regulated, as the prosthetic liner 10 now lies flushagainst the inside of the prosthetic socket 20.

A three-dimensional perspective view of the receiving part 25 with theinserted pneumatic piston 30 and the attachment element 17, which isassociated with the prosthetic liner 10, is shown in FIG. 5. Thereceiving part 25 may be attached to the prosthetic socket 20, notshown, and consist of a highly dimensionally stable material, forexample a light metal or fiber-reinforced plastic, which is outfittedwith a smooth surface in the cylinder region 21 or which has an insert,with which an appropriate friction pairing between the pneumatic piston30 and the cylinder region 21 can be made. Mechanical attachmentelements or receiving mechanisms for such attachment elements, forexample threads, bores, undercuts or the like, may be arranged or formedon the receiving part 25. In principle it is also possible to attach thereceiving part 25 to the prosthetic socket 20 by gluing, welding orvelcro connections.

FIG. 6 shows in a sectional representation a prosthetic liner 10 withthe distal end cap 16 and the pneumatic piston 30 inserted in theprosthetic socket and the use of the prosthetic liner 10 with themovably mounted pneumatic piston 30 arranged on the outside 15 thereofand attached thereon, in connection with a prosthetic socket 20. Theprosthetic socket 20 is substantially formed according to the outercontour of the stump, not shown, and formed in the embodiment shown froma dimensionally stable, air-tight material, for example afiber-reinforced plastic. The user puts on said prosthetic socket 20with the prosthetic liner 10 and the pneumatic piston 30, which isreversibly attached at the distal end 14 or integrally formed, throughthe proximal opening of the prosthetic socket 20. A force is therebyapplied to the pneumatic piston 30 through the application of the bodyweight in the distal direction. Even if the prosthetic socket 20 has anopen space at its distal end, which makes a precise introduction of thepneumatic piston 30 in the cylinder region 21 more difficult, thepneumatic piston 30 may be securely inserted into the cylinder region 21due to the insertion bevel 21. The attachment element 17 may beelastically formed, for example from a TPE, such that in this case adeformation of the attachment element 17 takes place during insertion ofthe pneumatic piston 30.

By means of body weight, the pneumatic piston 30 is inserted into thecylinder region 21 and the air within the closed volume formed therebyis expelled through the outlet valve 51. The outlet valve 51 is formedas a non-return valve or one-way check valve, which allows air oranother medium out of the volume 50 but blocks admission into the volume50 during a reverse movement of the pneumatic piston 30.

A volume is thereby spanned in the intermediary space 60 between theoutside of the prosthetic liner and the inside of the prosthetic socket,which volume can be evacuated via the pneumatic piston 30 by a repeatedapplication of force in the distal direction and a reverse unloadingmovement. Due to the resulting negative pressure, for example in a swingphase, a retaining force, albeit a small one, is also generated betweenthe pneumatic piston 30 and the prosthetic socket 20, so that theprosthetic liner 10, which lies adhering to the skin of the stump, isheld and guided on the prosthetic socket 20 by means of the pneumaticpiston 30, to which the prosthetic liner 10 is mechanically coupled. Themain retaining force is provided by the negative pressure in the space60 between the prosthetic liner and the prosthetic socket.

The receiving space 13 for the stump of the prosthesis user is alsoshown in the sectional view of FIG. 6. Through the pressing movement inthe distal direction, the pneumatic piston 30 is moved together with theprosthetic liner 10 in the direction of the distal end 22 of theprosthetic socket 20. The closed volume 50 present between the pneumaticpiston 30 and the cylinder region 21 is compressed, the gas containedwithin the volume 50, generally air, is pressed out, and the prostheticliner 10 can be pushed further in the direction of the distal end 22 ofthe prosthetic socket 20, until the pneumatic piston 30 has reached thebase of the cylinder region 21 at the distal end 22.

If the end position of the prosthetic liner 10 and therefore also of thepneumatic piston 30 within the prosthetic socket 20 is reached and thevolume 50 is minimized, a loading of the prosthetic liner 10 in theproximal direction leads to an increase in volume both of the closedvolume 50 and also of the intermediary space 60, whereby a relativenegative pressure results both with respect to the external environmentand also to the intermediary volume between the prosthetic socket 20 andthe prosthetic liner 10. This negative pressure on the one hand holdsthe pneumatic piston 30 in the cylinder region 21 and on the other handsuctions air from the intermediary space 60, which air, during loading,for example when taking a step, is pressed back out of the closed volume50. A mechanical barrier, for example an adjustable stop, a locking pinor another type of motion limitation may be provided againstunintentional sliding of the pneumatic piston 30 out of the cylinderregion 21.

In FIG. 7, a variant of the invention is shown which substantiallycorresponds to the construction of the device according to FIG. 6. Theprosthetic liner 10 is turned back on the outside around the proximaledge of the prosthetic socket 20 or provided with an outer sleeve whichis fixed to the outside of the prosthetic liner 10 and which forms agap, into which the prosthetic socket 20 can be inserted, so thatsealing also takes place on the outside of the prosthetic socket 20. Theturned-back prosthetic liner 10 or the sleeve arranged thereon areair-tightly formed; the sleeve may be glued, welded or pressed andadhered to the prosthetic liner 10. The volume enclosed by theprosthetic liner 20 and the prosthetic socket 10 is thereby maintainedsecurely in the intermediary space 60.

Instead of a valve or blocking mechanism in the pneumatic piston 30, itis provided that the blocking element 52 is not arranged in thepneumatic piston 30, but rather within the receiving part 25, in which afluidic connection from the intermediary space 60 to the closed volume50 is present in the form of a channel. The channel connects the suctionside of the pneumatic piston 30 to its pressure side. The blockingelement 52 is arranged within this fluidic connection in the form of anon-return valve, which prevents a reverse flow of air from the pressureside to the suction side. In a pulling-out movement of the prostheticliner 11 and thus a movement of the pneumatic piston 30 from the distalend position in the direction of the proximal insertion position, anegative pressure is created in the closed volume 50, through which airis suctioned from the intermediary space 60 into the closed volume 50.In an immersion movement of the pneumatic piston 30, the air in theclosed volume is then fed out through the outlet valve 51.

In FIG. 8, the receiving part 25 is shown in isolation with thepneumatic piston 30; the connecting channel between the intermediaryspace and the closed volume 50 is blocked via the blocking mechanism 52against an outflow from the closed volume, so that a pumping out of airfrom the intermediary space 60 between the prosthetic socket and theprosthetic liner is possible. The arrangement of a non-return valve 52in a separate channel at the receiving part 25 is advantageous withsmall dimensions of the pneumatic piston 30, as only a smallinstallation space is available in the pneumatic piston.

FIG. 9 shows a perspective view of parts of the prosthetic socket systemwith an end cap 16, which is shown without the associated prostheticliner. The attachment mechanism 17 is arranged on the distal end of theend cap 16 in the form of an attachment stud. The receiving part 25 isshown in isolation, without integration into a prosthetic socket. Thepneumatic piston 30 is inserted within the receiving part 25; theproximal end of the pneumatic piston 30 protrudes from the proximal endof the cylinder region of the receiving part 25. An annular pull-outsafety 70 is reversibly arranged on the proximal edge of the receivingpart 25, which pull-out safety 70 reduces the diameter of the cylinderregion within the receiving part and prevents the piston 30 from beingpulled out of the receiving part 25 during a pulling-out movement in theproximal direction.

A proximal end region is formed on the piston 30 as an attachmentmechanism 37 and has a spherical surface 370 in which four magnets 40are inserted. The magnets 40 are either also equipped with a sphericalsurface and are flush with the spherical surface 370 of the attachmentelement 37 or are inserted so as to be recessed therein.

The attachment mechanism 17 on the end cap 16 has a contact surface 170formed correspondingly to the spherical surface 370, wherein magnets areeither likewise inset in the attachment mechanism 17 or the attachmentmechanism 17 is formed as a magnet or at least comprises a magnetic, inparticular ferromagnetic material, so that the attachment mechanism 17can interact with the magnets 40 inside the pneumatic piston 30.Alternatively, it is possible that the pneumatic piston 30 has aconvexly curved, spherical surface 370 at the proximal end, and thecontact surface 170 has a concave formation corresponding thereto. It isalso possible that the magnets or only one magnet are/is arranged on theattachment element 17 of the prosthetic liner or the distal end cap 16,and the pneumatic piston 30 is ferromagnetic.

FIG. 10 shows the end cap 16 with the attachment element 17 screwedtherein and the spherically formed contact surface in a sectional view;the cylindrical region 21 can likewise be seen in the receiving part 25,as can the pneumatic piston 30 arranged thereon with the radially actingseal 31 and the magnets 40 mounted in the pneumatic piston 30 in theattachment mechanism 37. The magnets 40 are advantageously poled in thesame direction, so that they ensure a secure association with theattachment stud 17 and the contact surface 170, independently of therotational direction or rotational orientation of the pneumatic piston30 within the receiving part 25. Alternatively, it is possible to equipthe magnets 40 with an alternating polarity and to provide acorrespondingly differently poled magnet arrangement on the attachmentelement 17, so that a substantially equal alignment of pneumatic piston30 and prosthetic liner 10 is ensured after engaging contact.

The closed volume 50 is formed below the piston 30, a valve 33 isprovided within the piston 30, a channel with an outlet valve 51branches off from the closed volume 50, so that the air can escape fromthe closed volume. The air can be suctioned out of the prosthetic socketor the prosthetic liner by means of the pneumatic piston 30.

FIG. 11 shows the embodiment of FIG. 10 in the assembled state. Thepneumatic piston 30 is located in the upper position, the magnets 40pull the attachment element 17 toward the piston 30 and the contactsurface 170 is in complete contact with the spherical surface 370 of thepiston-side attachment mechanism 37.

FIG. 12 shows the arrangement according to FIG. 11 with the mountedpull-out safety 70, which is arranged in the receiving part 25, forexample screwed in. The upper edge of the pneumatic piston 30 restsagainst the lower edge of the pull-out safety, as is the case forexample during a swing phase. The end cap 16 is slightly tilted to thevertical axis, so that the contact surface 170 is displaced on thespherical surface 370 without losing contact. Due to the curvedsurfaces, it is possible that a relative movement, in particular atilting about three pivot axes which intersect at the center of thespherical surface 370, is possible without any problem.

FIG. 13 shows the arrangement according to FIG. 11 together with thepull-out safety 70 in the central, lowered position; the piston isdisplaced downward in the direction of the distal end of the cylinderregion 21; the closed volume 50 is reduced and the air has been pressedout of the outlet valve 51.

FIG. 14 shows the embodiment according to FIG. 13 in the distal endposition; the piston 30 is almost in contact with the cylinder base, theclosed volume 50 is minimal. The end cap 16 is almost in contact withthe proximal end of the receiving part 25.

The maximum piston stroke of the pneumatic piston 30 can be set via thescrew-in height or screw-in depth of the attachment element 17 in theend cap 16. If, during an unloading, for example during the swing phase,the pneumatic piston 30 is again displaced in the direction of thepull-out safety 70, air flows either from the prosthetic socket 20 orthe prosthetic liner 10 through the valve 30 into the increasing, closedvolume 50. In an opposite movement, for example during the stance phase,the closed volume 50 is again reduced, and the suctioned air is pressedout.

FIG. 15 shows the arrangement according to FIG. 12 in an oblique view;the end cap 16 is tilted to the vertical axis, the pull-out safety 70lies annularly about the cylinder region 21 of the receiving part 25 andprevents a situation in which, with separation of the force-lockingconnection between the prosthetic liner 10 and the pneumatic piston 30,the pneumatic piston 30 is moved out of the receiving part 25.

FIG. 16 shows a bottom view of the end cap 16 with the convex, sphericalcontact surface 170 and the underside of the receiving part 25 with theoutlet valve 51.

FIG. 17 shows the arrangement according to FIG. 16 in an obliqueperspective top view. The at least partially spherical surface 370 ofthe proximal end of the pneumatic piston 30 in the region of theattachment mechanism 37 can be seen, as can the recessed magnets 40.

FIG. 18 shows the arrangement according to FIG. 17 in an oblique sideview.

FIG. 19 shows the receiving part 25 in a perspective individualrepresentation. It can be seen that the pull-out safety 70 has twoopposite recesses 75, into which a tool can engage in order to attachthe pull-out safety 70 to the receiving part 25 in the region of thecylinder wall. In addition to a screwing into a thread which is formedin the cylinder section, wherein the pull-out safety 70 has an outerthread, the pull-out safety 70 may also be screwed or attached andpositively held via separate screws or attachment means to the receivingpart 25.

FIG. 20 shows the pneumatic piston 30 in an individual representationwith the four magnets arranged therein, the attachment mechanism 37 withthe spherical surface 370 and the radially arranged sealing element 31in the form of a sealing ring.

FIG. 21 shows the pneumatic piston 30 in a bottom view with the valve33, which allows an inflow of air into the closed volume 50 but preventsa reverse flow. The valve 33 may be formed as a hose valve or reed valveand serves as a non-return valve.

FIG. 22 shows the arrangement of the end cap 16 with the attachmentelement 17 as an attachment piston and the pneumatic piston 30 obliquelyfrom below.

FIG. 23 shows the pneumatic piston 30 with the attachment element 37,the sealing ring 31 before joining to the distal end cap 16.

1. A prosthetic liner for application on a stump, comprising: an elasticbase body which has a proximal opening, for insertion of the stump intoa receiving space, and a distal end; at least one pneumatic piston isarranged on an outside of the prosthetic liner.
 2. The prosthetic lineras claimed in claim 1, wherein the prosthetic liner has a blockingelement which prevents a reverse flow of air in the direction of theprosthetic liner.
 3. The prosthetic liner as claimed in claim 1, whereinthe pneumatic piston is formed as a separate component and is attachedto the prosthetic liner.
 4. The prosthetic liner as claimed in claim 1,wherein the pneumatic piston is reversibly attached at the distal end.5. The prosthetic liner as claimed in claim 2, wherein the blockingelement is formed as a valve or blocking lip.
 6. The prosthetic liner asclaimed in claim 1, further comprising a dimensionally stable end cap isarranged on the distal end of the prosthetic liner.
 7. The prostheticliner as claimed in claim 1, wherein the pneumatic piston has at leastone circumferential sealing element.
 8. The prosthetic liner as claimedin claim 1, wherein the pneumatic piston is movably attached to theprosthetic liner.
 9. The prosthetic liner as claimed in claim 1, whereinthe pneumatic piston is attached to the prosthetic liner via a balljoint or an elastic connection.
 10. The prosthetic liner as claimed inclaim 1, wherein the pneumatic piston is attached to the prostheticliner via at least one magnet.
 11. The prosthetic liner as claimed inclaim 10, wherein the pneumatic piston is connectably integrated via atleast one magnet into a prosthetic socket system composed of theprosthetic liner and a prosthetic socket.
 12. The prosthetic liner asclaimed in claim 10, wherein the pneumatic piston has an at leastpartially spherical surface.
 13. The prosthetic liner as claimed inclaim 10, further comprising an attachment element arranged on theprosthetic liner, via which the pneumatic piston is attached to theprosthetic liner and which has a contact surface formed to correspond toan at least partially spherical surface of the pneumatic piston.
 14. Aprosthetic socket system comprising: a prosthetic liner for applicationon a stump, the elastic liner comprising an elastic base body which hasa proximal opening, for insertion of the stump into a receiving space,and a distal end; a prosthetic socket which forms an intermediary spacewith the prosthetic liner; at least one pneumatic piston is arranged onthe outside of the prosthetic liner; wherein the prosthetic socket has acylinder region corresponding to the pneumatic piston, which cylinderregion is formed to receive the pneumatic piston and in which a closedvolume is formed in the coupled state of the prosthetic liner with theprosthetic socket, which closed volume is coupled to at least oneblocking element which prevents a reverse flow of air into theintermediary space.
 15. The prosthetic socket system as claimed in claim14, wherein the closed volume has a fluidic connection to at least oneblocking mechanism, which enables an outflow of air and prevents areverse flow.
 16. The prosthetic socket system as claimed in claim 14,wherein at least one of the closed volume and the intermediary space arefluidically connected to a ventilation mechanism for the introduction ofair.
 17. The prosthetic socket system as claimed in claim 14, whereinthe blocking element is arranged in at least one of the pneumaticpiston, a supply line from the intermediary space to the closed volumeand in a line from the closed volume to the environment.
 18. Theprosthetic socket system as claimed in claim 14, wherein the cylinderregion has an insertion bevel at its proximal end.
 19. The prostheticsocket system as claimed in claim 14, wherein a pull-out safety for thepneumatic piston is arranged at the proximal end of the cylinder region.20. A prosthetic liner for application on a stump, comprising: anelastic base body, comprising: a receiving space; a proximal opening forinsertion of the stump into the receiving space; a closed distal end; atleast one pneumatic piston arranged on an outside of the elastic basebody.